High-Stability Defect Engineering in MOFs via Chemical Induction for Advanced SERS Substrate Preparation

Induced vacancy defects have been strategically employed to enhance the performance of semiconductor substrates for surface-enhanced Raman scattering (SERS) applications such as chemical sensing and biosensing. However, maintaining these induced vacancy defects over prolonged use remains a significant challenge, as they tend to rapidly self-heal when exposed to air. In this study, we demonstrate that chemically induced oxygen vacancy (CIVO) defects can stabilize defect sites in the metal-organic framework (MOF) SERS substrate. Due to steric hindrance and the coordination environment surrounding the CIVO defects, these vacancies remain stable in atmospheric conditions for 100 days, in stark contrast to the short-lived photoinduced defects in conventional metal oxide semiconductors, which typically persist for only a few minutes. More significantly, the CIVO defect MOF substrates present a 3 orders of magnitude detection limit lower than the pristine MOF. Practical applications were tested by the CIVO defect MOF substrates, in which rhodamine 6G and <i>p</i>-aminoazobenzene molecules can be sensitively and quantitatively detected. This strategy of chemically induced stable oxygen vacancy defects exhibits broad applicability and is expected to further enhance the performance of MOF-based SERS substrates.